Cure of Hypogonadism after Removal of Prolactin-Secreting Adenomas in Men*

Abstract

Two men with PRL-secreting pituitary adenomas and hypogonadism were studied before and repeatedly after transsphenoidal adenomectomy. Serum PRL levels were elevated (220 and 300 ng/ml), with no rise after perphenazine or TRH administration. Serum testosterone levels were low (180 and 155 ng/dl) but increased to 800 and 520 after hCG administration. Serum gonadotropin levels were low normal. Clomiphene treatment in patient 2 was not associated with an appreciable increase in FSH, LH, or testosterone. One patient had a normal sperm count, while the other was azospermic. One week after surgery, serum PRL levels were normal, yet serum testosterone remained low. A gradual and steady rise in the serum testosterone level was noted during the postoperative period, reaching normal levels in 8 and 10 weeks. Clinical improvement paralleled the steady rise in the serum testosterone level. Repeat clomiphene administration in patient 2 resulted in a normal rise in serum FSH, LH, and testosterone 13 weeks after surgery. Sperm count increased from 0 to 22.3 million/ml in patient 2. The serum PRL response to the adminstration of TRH was subnormal (<50% increase) in both patients 1 week after surgery. This response became normal (>100% increase) at 2 weeks in patient 1 and remained so at 4 and 13 weeks. However, in patient 2, this response was still subnormal (80% increase) at 2 weeks but was normal at 5 and 13 weeks. In contrast to PRL, the serum TSH response to TRH administration remained normal 1 week after surgery and was not altered thereafter. PRL responses to perphenazine and L-dopa as well as the rest of the pituitary functions were normal in both patients 13 weeks after surgery. We conclude that the recovery of the hypothalamic-pituitarygonadal axis takes several weeks to occur after the correction of hyperprolactinemia. The recovery of normal lactotroph responsiveness from the inhibition caused by chronic hyperprolactinemia takes 2–5 weeks to occur.